1. Field of the Invention
The present invention relates to an image processing method and the apparatus thereof. More specifically, the present invention relates to a method for detecting page boundaries of a book document image with binding curvatures in the center part and the apparatus thereof, which are mainly applied to images gotten from flat-bed scanners, MFP, etc.
2. Description of Related Art
One problem with an image scanner is that when the scanner scans a spread book document, the bound portion of the book rises above a glass platen and thus is away from the focal plane of the scanner. Therefore, the image of the bound portion is distorted, shadowed, blurred or deteriorated, which is well known in the art. For a relatively thick book document, this problem becomes more serious.
In order to compensate for image deterioration in the bound portion, detecting accurate page boundaries is a very important step for the compensation techniques based on image processing. For example, the techniques disclosed in Japanese Patent Laid-Open Nos. 5-161000, 5-161001, 5-161002 and 6-164852 need to measure the height of the entire document pages by detection of page boundaries, and then execute correction over the entire curved pages. However, none of the above documents teaches a specific method for detection of page boundaries.
U.S. Pat. No. 6,330,050 B1 discloses a page boundary recognizing means that compares, image line by image line, image density data with an adaptive threshold over a pre-selected range to thereby calculate the positions of page boundaries. However, the disclosed means only aims to find page boundaries in the bound portion and can not deal with some complex images. For example, this means might fail for book document image with a book cover larger than book pages. Moreover, all the above documents do not deal with the problem of finding vertical page boundaries.
In view of the above, there is a need for a method for detecting page boundaries of a book document image and the apparatus thereof which are capable of accurately detecting complete page boundaries of book document images and/or capable of dealing with many kinds of complex conditions, including the above-mentioned large book cover, other disturbance objects existing near page boundaries, etc.